THE BRONX - The city’s Department of Parks and Recreation tested for a harmful algae bloom Monday at Van Cortlandt Park.

The green substance has been floating in a lake at the park for weeks. The city's Parks Department and other experts say fresh water lakes are susceptible to algae blooms.

"This is a normal situation for a fresh-water lake," says biologist and Bronx Community College teacher Vincent Chiappettea. 

The Parks Department says it will determine the next steps to take depending on its findings.